With the development of 3rd generation mobile telecommunications (3G) technology/the long term evolution (LTE) technology, a higher requirement of time synchronization performance for communication network is desirable. There are some problems in the existing global positioning system (GPS) for time synchronization, such as the difficulties in location for installation, maintenance and laying feeder cable, and the high safety hazard and cost, hence how to realize a high-accuracy ground time synchronization is very important.
1588V2 high-accuracy time-recovery technology comes into being under the requirement for the high-accuracy ground time synchronization. The 1588V2 high-accuracy time-recovery technology is realized basing on the symmetry of the back-and-forth optical fiber links (hereinafter referred to as symmetry of optical fibers). In the process of cutting in and maintaining a network, the slight asymmetry of the back-and-forth optical fiber links (hereinafter referred to as symmetry of optical fibers) may be introduced, hence there may occur error and effect accuracy if employing the 1588V2 high-accuracy time-recovery technology. Therefore, the detection of symmetry of optical fibers affects the accuracy of the 1588V2 high-accuracy time-recovery technology.
At present, the detection for the symmetry of the optical fiber in network is mainly implemented manually, thereby producing a high manual maintenance cost and a long positioning time. In addition, once asymmetry of optical fibers occurs in the network, a long-time detection caused accordingly may affect the service.